The term is a lot older than 9/11/2001. The most common usage was the point on the ground directly under an airburst nuclear bomb, either in combat or a test explosion. I don't know if it was used for bombing locations previous to that.
Isn't there some restaurant in the Bronx that's serving salt and transfat for Bloomberg to harass?
you are right on the history of the term - but it has escalated since 9-11 and seems to be used more and more for the area that is the epicenter of any number of events.
My point was the Bloomberg was trying to remove a part of the language that is ingrained way above and beyond this area of his city — further demonstrating his endless gall and arrogance.